1. Field of the Invention
The present invention relates generally to electrical switches. In particular, the present invention relates to seesaw type switches used in automobiles, for example, as power window switches.
2. Description of the Related Art
A seesaw type switch available conventionally is shown in FIG. 15(a) to FIG. 15(c) and, for example, in Japanese Patent Publication No. 9-167543. FIG. 15(a) is an exploded perspective view of the conventional seesaw type switch, FIG. 15(b) is a plan view thereof, and FIG. 15(c) is a cross section view thereof as viewed along lines SAxe2x80x94SA in FIG. 15(b).
As shown in FIGS. 15(a) to 15(c), the conventional seesaw type switch 201 has a knob fixture 205 installed on the top of a case 203, and a switch knob 209 is supported on a support pin 207 of the knob fixture 205. The switch knob 209 is capable of oscillation in fore and aft directions on the support pin 207. The switch knob 209 is provided with an operation lever 211, which is inserted into the case 203. The lower edge of the operation lever 211 is engaged with an interlock pin 215 on a movable board 213. Therefore, when the switch knob 209 is operated to oscillate fore and aft, the interlock pin 215 is operated via the operation lever 211, whereas switching operation can be performed by using the movable board 213.
A light source 217 is installed in the case 203 as shown in FIG. 15(c). The switch knob 209 is installed with an indicator that permeates light, wherein illumination light from the light source 217 permeating through the indicator allows easy viewing of the indicator in the switch knob 209 even at night.
However, the above construction has the top of the knob fixture 205 opening widely, allowing dust and other foreign materials to enter into the case 203 from the opening of the knob fixture 205, causing them to deposit on movable contacts and fixed contacts, thereby leading to the risk of defective operation of the movable board 213 and defects in the contacts. Particularly because the operation lever 211 of the switch knob 209 is inserted from the knob fixture 205, whose oscillating operation operates the movable board 213, the opening of the knob fixture 205 was forced to be large. At the same time, because illumination light from the light source 217 installed in the case 203 is passed through the knob fixture 205 to direct the light to the indicator of the switch knob 209, the opening of the knob fixture 205 was forced to be large also from this aspect. Therefore, it was not possible to avoid invasion of dust.
The present invention provides a seesaw type switch with high dust-proof performance, while making possible the oscillating operation of the switch knob and indication by light permeation.
According to a first aspect of the present invention, a seesaw type switch is provided in which an operation lever of a switch knob having a light permeating indicator is inserted into a cylindrical knob fixture comprising of fore-to-aft and left-to-right walls and having an opening from the opening, and the switch knob is supported on the left-to-right walls so that the knob can be operated in oscillation, the seesaw type switch being characterized in that a boss having a curved surface concentric with the center of the support and existing over a light permeating indicator zone is provided, fore-to-aft facing sections facing contiguously with the curved surface on both sides before and behind the support center are provided on fore-to-aft walls of the knob fixture, at least one of left-to-right curved surfaces facing contiguously along both sides of the curved surface of the left-to-right facing boss and the outer surface of the left-to-right walls facing contiguously with a plate drooping from the left to right of the operation knob is provided on the left-to-right walls of the knob fixture, and the part existing at least on the light permeating indicator zone of the boss is formed by using a light permeating material.
According to a second aspect of the present invention, the fore-to-aft facing part is an inner top of the fore-to-aft wall of the knob fixture, and the left-to-right curved surface is formed over the inner top of the fore-to-aft wall.
According to a third aspect of the present invention, an operation lever of a switch knob having a light permeating indicator is inserted into a cylindrical knob fixture having an opening from the opening, and the switch knob is supported so that the knob can be operated in oscillation. In this case, a boss having a curved surface concentric with the center of the support is provided on the operation lever side of the switch knob, a closely facing part contiguous with the curved surface on both fore and aft sides of the support center is provided on the knob fixture, a closing part to close the inner wall surface with the inner left-to-right wall surface and the inner rear wall surface with the inner left-to-right wall surface is provided, and the part existing at least in the light permeating indicator zone in the closing part is formed by using a light permeating material.
According to a fourth aspect of the present invention, the closing part of a seesaw type switch is equipped with a run off on the lever side to run off from interference of the operation lever in oscillation by forming a shape to alienate gradually from the support center more on the operation lever side than from the run off on the opening side to run off from interference of the switch knob in oscillation and the closely facing part.
Numerous other objects of the present invention will be apparent to those skilled in this art from the following description wherein there is shown and described an embodiment of the present invention, simply by way of illustration of one of the modes best suited to carry out the invention. As will be realized, the invention is capable of other different embodiments, and its several details are capable of modification in various obvious aspects without departing from the invention. Accordingly, the drawings and description should be regarded as illustrative in nature and not restrictive.